This invention relates to an image processing method that digitally reads an image exposed and developed on a taking light-sensitive material and which performs image processing on the basis of the acquired digital image.
Heretofore, the images recorded on photographic films such as negatives and reversals (which are hereunder referred to simply as xe2x80x9cfilmsxe2x80x9d) have been commonly printed on light-sensitive materials (photographic paper) by means of direct (analog) exposure in which the film image is projected onto the light-sensitive material to achieve its areal exposure.
A new technology has recently been introduced and this is a printer that relies upon digital exposure. Briefly, the image recorded on a film is read photoelectrically, converted to digital signals and subjected to various image processing schemes to produce output image data for recording purposes; recording light modulated in accordance with the output image data is used to scan and expose a light-sensitive material to record a latent image, which is subsequently developed to produce a (finished) print. The printer operating on this principle has been commercialized as a digital photoprinter.
In the digital photoprinter, images can be processed as digital image data to determine the exposure conditions for printing, so various operations including the correction of washed-out highlights and flat (dull) shadows due to the taking of pictures with backlight or an electronic flash, sharpening, the correction of color failure and density failure, the correction of underexposure and overexposure, and the correction of insufficiency of marginal luminance can be performed in an effective manner to produce prints of the high quality that has been unattainable by the conventional direct exposure.
Having these features, the digital photoprinter is basically composed of the following units: a scanner (image reading apparatus) that reads the image on a film photoelectrically; an image processing apparatus that processes the captured image to produce output image data (exposing conditions) for recording purposes; and a printer (image recording apparatus) that scan exposes a light-sensitive material in accordance with the output image data and which then performs development and other necessary processing to produce a print.
In the scanner, reading light issuing from an illuminant is allowed to be incident on a film, from which projected light bearing the image recorded on the film is produced and focused by an imaging lens to form a sharp image on an image sensor such as a CCD sensor; the image is then captured by photoelectric conversion and sent to the image processing apparatus as input image data (image data signals) from the film after being optionally subjected to various image processing schemes.
In the image processing apparatus, image processing conditions are set on the basis of the input image data captured with the scanner and image processing as determined by the thus set conditions is performed on the captured input image data and the resulting output image data (exposing conditions) for recording purposes are sent to the printer.
In the printer, if it is of a type that relies upon exposure by scanning with an optical beam, the latter is modulated in accordance with the output image data from the image processing apparatus and a light-sensitive material is subjected to two-dimensional scan exposure (printing) of a light-sensitive material to form a latent image, which is subsequently developed and given other specified treatments to produce a print (photograph) reproducing the image that was recorded on the film.
Thus, the digital photoprinter does more than outputting prints reproducing the images recorded on films; even if the film image is not highly reproducible for the reason that it was taken under inappropriate conditions, the digital photoprinter performs digital image processing to correct scenes taken with backlight, high contrast scenes, underexposed negatives, low sharpness, the insufficiency of the marginal luminance and other undesired phenomena, thereby facilitating the outputting of prints that reproduce beautiful and high-quality images.
When outputting photographic prints, the digital photoprinter processes the image data for each frame as read from the original film. To this end, gray balance, color balance and various other image processing conditions that concern color and/or density are adjusted either automatically or manually by the operator such that they are at all times optimal for the image in each frame. If necessary, to give an even better finish, the operator makes fine adjustment of the image processing conditions including gray balance. To obtain prints of the same color and/or density from the same original film, it is desired to reproduce the gray balance and other image processing conditions that were adjusted by the operator.
For instance, if reprinting is ordered at the same photo shop that produced simultaneous prints, it is necessary that the simultaneous prints and the reprints be finished to have the same color and/or density. This requirement must also be met in the case where reprinting and simultaneous printing are ordered at different photo shops. To meet this need, it is desired that the gray balance condition used in making the simultaneous prints be faithfully reproduced in the reprints. Consider, for example, the case of reading the original film with a convenient film scanner at hand, applying color adjustments to make a proof print, reading the same original film with a different scanner, say, a high-performance scanner, and making a high volume of prints such as postcard prints that have the same color and/or density balance as the proof print. To be successful in this case, the gray balance condition is desirably reproduced.
In order that the image recorded in each frame of a taking film is processed to an appropriate finish having a good gray balance, Unexamined Published Japanese Patent Application (kokai) No. 197577/1997 proposed a method characterized by printing control patches such as gray patches in the nonimage area of the film, developing the film and reading the control patches with a scanner to estimate the characteristic curve (xcex3 characteristic) of the film or correcting the upset in the gray balance due to the time-dependent change (deterioration with the passage of time) of the characteristic curve.
According to the specification of commonly assigned Japanese Patent Application No. 118492/1997, calibration patterns such as gray patches and color patches are preliminarily printed in the nonimage area of a taking film and, after development, the calibration patterns are read with a scanner and balance is struck such that they are given an appropriate finish (for example, the image data for all frames in a roll of original film are adjusted such that grays are correctly reproduced) and this enables perfect color adjustment of the image in each frame.
The above-described techniques ensure that when the images in the frames of a roll of taking film are read with a scanner, an appropriate gray balance is struck for each of the captured images to correct any upset in gray balance due to either deterioration with the passage of time or the characteristics of the film. However, various light sources including daylight, a tungsten lamp and a fluorescent lamp are used to take the images in film frames and it is impossible to correct such variations in the illuminant with reference to calibration patterns consisting of gray patches. If all frames are corrected in terms of calibration patterns, the obtained prints are characterized by xe2x80x9cloweredxe2x80x9d correction.
In this situation, an auto-setup algorithm is commonly employed to estimate the shooting light source from the characteristic quantities for each frame and perform optimal color adjustment. In a desirable mode, the finished image is displayed on a verification monitor and if the operator finds the need to adjust it, he or she performs the necessary correction with color keys and adjusts the image such as to produce optionally finished prints.
However, the techniques described above are incapable of faithful reproduction of gray balance. For example, it is considerably difficult to process reprints to have the same finish as simultaneous prints. Particularly in the case of post cards, the best conditions for trial printing cannot be reproduced in the second (final) printing.
Another problem is that even if the parameters to the gray balance condition as one of the best conditions for the making of simultaneous prints and for trial printing are stored in a memory and accessed when reprints are ordered or during the second (final) printing, no two prints are guaranteed to have the same finish unless the scanner characteristics are identical between the two instances.
Even if the same scanner is used, faithful reproduction of gray balance is impossible if the scanner characteristics change with time. Even if two scanners of the same model are used, the same problem occurs if they have instrumental error in their characteristics. Of course, gray balance cannot be reproduced faithfully if two different scanners are used.
The present invention has been accomplished under these circumstances and has as an object providing an image processing method which is capable of faithful reproduction of gray balance in all situations to be encountered, particularly in the three cases mentioned above.
More particularly, the present invention has the object providing the image processing method capable of reproducing image processing condition concerning at least one of color and density such as the gray balance which is adjusted by operator and obtaining the same image processing result, even if the same scanner is used and the print timing is different, even if the different scanners of the same model which have instrumental error, or even if the different scanners of the different model.
The stated object of the invention can be attained by an image processing method, comprising the steps of:
reading digitally frame images exposed and developed in frames of a taking light-sensitive material and calibration patterns exposed outside image exposure areas of the taking light-sensitive material at least one of before and after exposure of the frame images and developed to obtain digital image data for the frame images and digital calibration pattern data at an image reading mode;
adjusting image processing condition concerning at least one of color and density for processing the frame images based on a relative value to the obtained digital calibration pattern data; and
thereafter processing the digital image data on the frame images under the thus adjusted image processing condition.
Preferably, the image reading mode comprises a first image reading mode and a second reading mode, and the adjust of the image processing condition based on the relative value to the digital calibration pattern data is performed by the steps of:
storing as the relative value the image processing condition adjusted during the first image reading mode; and
modifying the image processing condition using the relative value stored during the first image reading mode and the digital calibration pattern data that is read during the second image reading mode, in such a way that image processing result concerning at least one of the color and the density in the second image reading mode agrees with the image processing result concerning at least one of the color and the density in the first image reading mode.
Preferably, the storage of the relative value during the first image reading mode is performed by the steps of:
setting for the digital image data on each frame image the image processing condition of each frame as determined through color adjustment by either auto-setup or the operator or both; and
determining as the relative value a difference between the set image processing condition and the image processing condition based on the digital calibration pattern data as read during the first image reading mode.
Preferably, the modification of the image processing condition during the second image reading mode is performed by modifying the relative value under the image processing condition based on the acquired digital calibration pattern data in the second image reading mode.
Preferably, the first and second image reading modes are carried out at different image reproductions by a same scanner for image reading,
Preferably, the first and second image reading modes are carried out with different scanners of a same model for image reading.
Preferably, the first and second image reading modes are carried out with different scanners of different models for image reading.
Preferably, the storage of the relative values during the first image reading mode is performed by either magnetic recording or recording in an IC cartridge.
Preferably, the calibration patterns are gray patches, the image processing condition is gray balance, and the relative value is difference between the gray balance as set through color adjustment by either the auto-setup or an operator or both and the gray balance based on digital data on the gray patches.